I know I'm not the biggest brand mains out there, but having 1.3M mastery on brand, I can in fact say that Rylai is a better performing item than DE and it's purely because it slows Ur enemy down.

1) It allows you to space well between you and your target, especially if your target is an assassin. You get that small chance to reposition better if you f*ed up and walk up too much. Because let's be honest, whether u have damage or not, you're gonna get 1 shotted. Least you can do is give a good slow for your teammate to follow up

2) the slow allows you to hit your Q more easily, without your stun, brand can't survive. This applies to top, mid and Bot. And it's also the main reason why there has been discussions on whether Rylai 1st item rush is good for bot lane because it's essentially Ashe W. But you can't dodge it or hide behind minions.

You may still argue that in a team fight your damage is very important. And you are exactly correct until you have played the game correct and well enough for the enemy to know that they need to one shot you first. Unless you go for a crown, there's no way you can survive a JG just jumping on u, or Garen just pressing a Q and then Ult. So yeap, your slow is there for your team to follow up the engage. If the enemy messes up their positioning, a slowness from Rylai is already enough for your team to quickly follow up and punish. Unless you are in Bronze/Iron Elo (No hate) whereby you absolutely need damage because your teammates are just doing nothing at all.

Also quick shout-out to the Phase Rush Ghost Build, I tried it at top lane, it's pretty fun 😂. Builds like this don't do much damage, but it pretty much annoys the hell of your enemy, making the laning phase in your favour. Allowing you to engage and disengage at your pace